Steel plate lifting tongs



Oct. 17, 1944. c; RENFROE 2,360,366

STEEL PLATE LIFTING Tones Filed Sept. 16, 1943 2 Sheets-Sheet 1 Oct. 17, 1944. c, REN-FRQE 2,360,366

STEEL PLATE LIFTING TONGS Filed Sept, 16, 1943 2 Sheets-Sheet 2 awe/whom J C fienfroe;

Patented Oct. 17, 1944 UNITED STATES PATENT OFFICE STEEL PLATE LIFTING TONGS Joseph C. Renfroe, Jacksonville, Fla.

Application September 16, 1943, Serial No. 502,676

8 Claims.

This invention relates to plate lifting tongs, and more particularly to a pair of tongs which will be employed in shipyards for positively clamping on a steel plate weighing many tons, and when supported on a lifting cable, will safely and. efficiently transport the steel plate to the desired place on a construction job where a manual unlocking of the clamp will be required before the same may be released from the steel plate.

My present invention constitutes an improvement over my earlier application bearing Serial No. 499,533, filed on August 21, 1943.

An object of my invention is to provide an improved steel plate lifting tongs which is so designed that when a steel plate is inserted between the jaws of the clamp, the raising of the cable to which the clamp is secured, will positively cause the jaws to clamp on to the opposite sides of the plate, and to support the same in locked position until a manual unlocking of the clamp is effected.

Another object of my invention is to provide an improved steel plate lifting tongs or clamp having a hard steel swiveled die or jaw and a cooperating hard steel pivoted clamping jaw, said clamping jaw being connected by means of a link to a sliding link to which the lifting cable is attached, in such a, manner that the plate being lifted will be in a direct line with the lifting cable, as distinguished from a clamp which will hold a plate off center and at an angle to the line of pull.

Another object of my invention is to provide an automatically clamping and self-locking steel plate lifting-clamp or tongs, which will be highly efficient in use and relatively inexpensive to manufacture.

Other objects will appear as the description proceeds.

In the accompanying drawings which form a part of my application,

Figure 1 is a side elevation of my improved steel plate clamp or tongs;

Figure 2 is an edge view partly in section of my improved steel plate clamp or tongs;

Figure 3 is a transverse sectional view through my improved steel plate clamp or tongs;

Figure 4 is a sectional view taken on the line 4-4 of Figure 3;

Figure 5 is a side elevation of the locking pawl;

Figure 6 is a front elevation of the fixed or swivel jaw, and

Figure 7 is a sectional view taken on the line l'! of Figure 6. I

Like characters of reference are used throughout the following specification and the accompanying drawings to designate corresponding parts.

In carrying out my invention, I provide an improved form of tongs or clamp having a body I of inverted U-shape and formed with an upwardly extending integral head or bar 2, which is provided with a vertically extending bearing slot 3 which is arranged in vertical alinement with the slot formed in the lower surface or edge of the body I into which the steel plate to be lifted is inserted. A hard steel swiveled die or jaw 4 is received within a stepped recess in the inner surface of the slot formed in the lower edge of the body I, and has a reduced shank 5 which cooperates with a cotter pin or key 6 extending through the body, as clearly illustrated in Figures 1 and 3 of the drawings. The steel plate engaging surface of the die or jaw 4 is formed with a plurality of concentrically arranged alternate ridges 24 to more firmly hold a steel plate when supported by the clamp or tongs. A pivoted cam jaw I is pivoted on a bearing pin 8 extending through the body I, and cooperates with the fixed jaw in the opposite side of the slot in the lower edge of the clamp body I.

The shackle 9 having spaced depending arms is arranged to fit over the opposite sides of the head or bar 2 and to receive the cross bearing pin l0 which will be slidably received within the slot 3 in said head or bar 2, said shackle also being formed at its upper end with an enlarger eye 23 into which the hook (not shown) on the lifting cable will be placed. A pivot pin II will extend through the outer or free end of the pivoted cam jaw 1, and further supports the spaced connecting links l2, whose opposite terminals are mounted upon the outer ends of the bearing pin l0. The upper surface of the cam jaw l is formed with a toothed rack l3, while the steel plate engaging surface of the cam jaw 1 if desired may be suitably milled or roughened as at l4 to firmly contact and hold the steel plate in clamped position within the plate receiving slot in the lower edge of the body I. The rack engaging and locking pawl is adapted to slide within the tracks or bearing slots l6 formed within the body I in a vertical direction and parallel with the slot into which the steel plate is inserted. The locking ratchet or pawl l1 extends transversely between the tracks IS in the body and is formed with an upwardly extending shank portion I8 which is slotted at its upper end to receive the finger engaging head I9 which is held in place by means of the cross pin 20. A laterally and downwardly extending locking ear 2i is formed on the side of the head l9 next to the head or bar 2 and is adapted to be swung into or out of the locking keeper slot or recess 22 formed in the adjacent surface of the said head or bar 2. A tensioning coil spring 24 is positioned about the shank portion I8 of the locking ratchet or pawl 17 and urges it into engagement with the toothed rack E3 on the pivoted cam jaw 1, so that when a steel plate is inserted within the slot in the lower edge of the clamp body I, the upward pull of the cable supporting the clamp will immediately act through the associated linkage to cam the jaw 1 into firm engagement with the steel plate, while the locking ratchet or pawl l1 engaging the rack l3 keeps the cooperating jaws in locked and clamped position until the finger operated head I9 is grasped and raised up against the action .of the coil spring 24, and the locking ear 2| slipped into the adjacent keeper slot 22, whereupon the clamp may be used independently of the cam jaw locking mechanism. The withdrawal of the locking ear from the keeper slot makes the locking mechanism come immediately into automatic operation again.

While I have described one specific form of steel plate engaging clamp or tongs, it will be apparent that many minor changes in detail of construction may be resorted to without departure from the spirit of the invention. It will be further apparent that the clamp body and integrally formed bar are formed in one casting, also that due to the alinement of the lifting eye, pivot pin or bearing .pin I 0, and the plate receiving slot, when the clamp is elevated, the plate Within it will also be in vertical alinement, which construction provides. thestrongest clamp arrangement, and one which will clamp at twice the force of any other clamp using other forms of linkage. The use of the swivel jaw is found to more firmly clamp a steel plate than when a fixed jaw is employed.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A device of the character described comprising an integrally formed bod portion and upwardly extending slotted head or bar, said body being formed with a plate receiving slot in its lower edge in vertical alinement with the bearing slot in the integral head or bar, a swivel die or jaw positioned in said body at one side of said plate receiving slot, a pivoted cam jaw mounted in the body at the other side of the plate receiving slot, a shackle slidably supported in the slotted head or bar, and links connected between the pivoted jaw and said shackle, whereby upward movement of the shackle will cause the clamping action of the pivoted jaw to secure a steel plate when in the plate receiving slot.

2. A steel plate lifting clamp or tongs comprising a slotted body,- a bearing bar formed integrally with said body and provided with a bearing slot in alinement with the slot in said body,

and a pair of clamping jaws carried by the body at the opposite sides of the slot cooperating with a shackle vertically mounted in the bearing slot in the bearing bar for clamping a steel plate in the bodyslot upon the upward movement of the said shackle.

3. A device of the character described comprisin a slotted body and an integrally formed slotted bearing head or bar, a swivel jaw carried by the body, a pivoted cam jaw carried b the body, a shackle mounted for vertical movement in the bearing slot and having operative connection with the pivoted jaw, and the slots in the body and bearing bar being in vertical alinement. H n

4. The subject matter as claimed in claim 3, and means for positively locking the pivoted J'a'w when it engages a sheet of steel when placed in the body slot.

5. The subject matter as claimed in claim 3, and automatic locking means for locking the pivoted jaw in clamped position.

6. The subject matter as claimed in claim 3, automatic locking means for locking the pivoted jaw in clamped position, and manually controlled means for disengaging and holding said locking means disengaged so that the clamp may be used either with or without the use of the automatic jaw locking mechanism.

7. The subject matter as claimed in claim 3, automatic locking means including spring tensioning means for locking the pivoted jaw in clamped position, and manually controlled means for releasing the automatic locking means and for holding the same in released position when it is desired to use the clamp without said locking means.

8. A device of thejchara'cter described comprising a steel plate lifting clamp having a pivoted jaw and a swivel jaw, latch means for holding the pivoted jaw in a number of different positions, and manually controlled means for releasing the latch means for holding the same in released position.

JOSEPH C. RENFROE. 

